A work can't claim copyright on another work. "Viral licences" aren't. What they can do is require distribution of a merged work to only be under their conditions. An image on an article page is an aggregation of two separate works, the text and picture.
There is a difference between restricting what work your work can be incorporated in, and claiming copyright. The free art license isn't saying "if you include this image in your work, then your work is automatically under our license" it's saying "the only work you can include this image in is work released under this license" - they are very different things.
I don't see how the page being an aggregation of two separate works is relevant - the page as a whole is a work, and the Free Art image has been incorporated into it.